From cca48f69b04462c5c9bfefd34443e0b8401dbd6c Mon Sep 17 00:00:00 2001
From: 21E14 <21xe14@gmail.com>
Date: Sat, 1 Nov 2014 17:42:12 -0400
Subject: [PATCH 1/2] Reset setBlockIndexCandidates once block index db loaded

---
 src/main.cpp | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 008a05910..1ba17614d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1949,6 +1949,16 @@ static CBlockIndex* FindMostWorkChain() {
     } while(true);
 }
 
+// Delete all entries in setBlockIndexCandidates that are worse than the current tip.
+static void PruneBlockIndexCandidates() {
+    // Note that we can't delete the current block itself, as we may need to return to it later in case a
+    // reorganization to a better block fails.
+    std::set<CBlockIndex*, CBlockIndexWorkComparator>::iterator it = setBlockIndexCandidates.begin();
+    while (setBlockIndexCandidates.value_comp()(*it, chainActive.Tip())) {
+        setBlockIndexCandidates.erase(it++);
+    }
+}
+
 // Try to make some progress towards making pindexMostWork the active block.
 // pblock is either NULL or a pointer to a CBlock corresponding to pindexMostWork.
 static bool ActivateBestChainStep(CValidationState &state, CBlockIndex *pindexMostWork, CBlock *pblock) {
@@ -1996,13 +2006,7 @@ static bool ActivateBestChainStep(CValidationState &state, CBlockIndex *pindexMo
                 return false;
             }
         } else {
-            // Delete all entries in setBlockIndexCandidates that are worse than our new current block.
-            // Note that we can't delete the current block itself, as we may need to return to it later in case a
-            // reorganization to a better block fails.
-            std::set<CBlockIndex*, CBlockIndexWorkComparator>::iterator it = setBlockIndexCandidates.begin();
-            while (setBlockIndexCandidates.value_comp()(*it, chainActive.Tip())) {
-                setBlockIndexCandidates.erase(it++);
-            }
+            PruneBlockIndexCandidates();
             // Either the current tip or a successor of it we're working towards is left in setBlockIndexCandidates.
             assert(!setBlockIndexCandidates.empty());
             if (!pindexOldTip || chainActive.Tip()->nChainWork > pindexOldTip->nChainWork) {
@@ -2860,6 +2864,9 @@ bool static LoadBlockIndexDB()
     if (it == mapBlockIndex.end())
         return true;
     chainActive.SetTip(it->second);
+
+    PruneBlockIndexCandidates();
+
     LogPrintf("LoadBlockIndexDB(): hashBestChain=%s height=%d date=%s progress=%f\n",
         chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(),
         DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()),

From 34559c7c73e3ce67baea0d88ba74b0988b55142d Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Thu, 20 Nov 2014 12:43:50 +0100
Subject: [PATCH 2/2] Make PruneBlockIndexCandidates safer

---
 src/main.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 1ba17614d..ac65a4ac2 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1954,9 +1954,11 @@ static void PruneBlockIndexCandidates() {
     // Note that we can't delete the current block itself, as we may need to return to it later in case a
     // reorganization to a better block fails.
     std::set<CBlockIndex*, CBlockIndexWorkComparator>::iterator it = setBlockIndexCandidates.begin();
-    while (setBlockIndexCandidates.value_comp()(*it, chainActive.Tip())) {
+    while (it != setBlockIndexCandidates.end() && setBlockIndexCandidates.value_comp()(*it, chainActive.Tip())) {
         setBlockIndexCandidates.erase(it++);
     }
+    // Either the current tip or a successor of it we're working towards is left in setBlockIndexCandidates.
+    assert(!setBlockIndexCandidates.empty());
 }
 
 // Try to make some progress towards making pindexMostWork the active block.
@@ -2007,8 +2009,6 @@ static bool ActivateBestChainStep(CValidationState &state, CBlockIndex *pindexMo
             }
         } else {
             PruneBlockIndexCandidates();
-            // Either the current tip or a successor of it we're working towards is left in setBlockIndexCandidates.
-            assert(!setBlockIndexCandidates.empty());
             if (!pindexOldTip || chainActive.Tip()->nChainWork > pindexOldTip->nChainWork) {
                 // We're in a better position than we were. Return temporarily to release the lock.
                 fContinue = false;